Product labels have played an important role in communicating information to people and devices. Typically, the primary purpose of labels is to provide information such as: directions for use; product identification; trademarks; promotions; production; freshness or “use-by” dates; product authentication; and other product-related information. Existing labels generally convey static information such as type, logos, graphics and product identification information, such as barcodes and the like. Although variable information (e.g., product serial numbers) has been introduced to individual parts of some existing labels, once such labels are produced, the image cannot be changed without removing layers or physically altering the surface.
Though it is highly desirable to include an active image in product labels, few effective and affordable methods currently achieve this function. Currently, labels are generally produced in extremely large volumes at very low cost using traditional printing processes. Thus, the desire to include active image functionality to the labels through existing methods has also been limited by the inability to introduce an active image without modifying the existing manufacturing processes and absorbing the associated costs. The desire to provide active image functionality through existing methods is also present for applications that are not labels in the usual sense (i.e. labels are usually affixed to the product or its container) but are closely associated with a product or service; for example, a timer token packaged with a product indicating elapsed time relating to product use, variable use instructions, or other active package inserts may be produced to accompany product packaging or be constructed directly on product packaging.
Some methods exist in the art to provide active image labels through the use of thermochromic or photochromic inks that respond to environmental conditions such as temperature or light. However, the utility of such approaches is limited due to the extreme environmental changes required to alter the image. Likewise, optically variable images have been used to add active components to labels, but the utility of such approaches is limited by the inability to control the activation of an alternate image.
Other active labels implement methods to communicate information from the label to a machine through the use of RF energy for providing information. Although this method provides additional information to compatible machines, it does not allow additional communication to humans, because the stored information is not communicated visually.
Another approach for providing active images in labels has been through thin displays. Displays are generally differentiated from print by the capability to actively change an image. Print is considered static, because once the image is produced, it cannot change or be influenced by the external environment. Displays, on the other hand, have the ability to change, based on a given input or environmental condition.
Another differentiating factor between displays and traditional printed labels is cost. The cost for traditional print is very low due to the large volumes produced; the substrate used (paper) and the production processes. Typical printing processes run at very high speeds and use low cost substrates to convey information at the extremely low cost point necessary for widespread application. Print processes can easily change over from one print job to the next. Trillions of square feet of static print are produced annually via these processes on a global basis. They include newspapers, product packaging, product labels, publications and many other applications.
By contrast, conventional displays are typically produced by traditional electronic assembly processes. Liquid Crystal Displays (LCDs) and Organic Light Emitting Diodes (OLEDs) are produced in conventional electronic fabrication plants, using micro-assembly techniques, and are built on polarized glass. Extreme precision is required on the disposition of the active components, and environmental conditions also must be tightly controlled.
Displays can vary in complexity from simple, single dot or icon images to full-color video. The information content depends on the purpose of the specific display and the particular communication need. Examples may include a single icon that communicates a desired warning message, an alpha-numeric display that communicates words and numeric values or a matrix addressable display that communicates more complex images such as maps or pictures. The rate at which the display can change or update determines the stream of information which can be updated.
Display technology has evolved to meet society's need for increased information. Of particular interest is the need to provide displays that are thin and withstand flexing at a cost that allows widespread implementation on disposable items in extremely high volumes.
Several attempts have been made to produce such displays. LCDs were developed using glass as the substrate. Some recent flexible LCD developments achieve the necessary flexibility but are still extremely costly to produce. Other flexible technologies include electrophoretic displays such as those described in U.S. Pat. No. 6,445,489. Electrophoretic displays exhibit the necessary flexibility but currently cannot be produced with existing high-volume and low-cost printing production processes.
Other advances have been made in higher content displays as well. OLEDs provide color and very high resolution. OLEDs can be made flexible but require significant power and are most suitable for high value, high content applications.
As described, printing techniques generally benefit from cost savings and production efficiencies. Electro-phoretic displays take advantage of some of the print manufacturing process benefits. This technology may implement screen printing to deposit the active layer between a conductive front and backplane. However, relatively thick layers of ink are required and cell thickness must be tightly controlled. Moreover, operating voltages for electro-phoretic displays are high, typically more than 7 volts, which requires additional components to alter the power from traditional batteries.
Thus, there is a need for a thin and flexible, layered label structure with built-in electronic functionality, such as an embedded active display and associated electronics for driving the display. This need also extends to non-label structures as well, such as timer tokens, variable instructions, electrochromic holographic structures, or other active structures. There is also a need for such label and non-label structures with active displays that visually convey desired information to humans. Moreover, there is a need to produce a structure with electronic functionality through low-cost methods, such as printing processes, that allow for widespread implementation on disposable items in extremely high volumes. There is also a need for the structure with electronic functionality to be powered by a relatively low voltage and/or current.